Preparation And Evaluation Of Molecularly Imprinted Monolith Under Molecular Crowding Conditions And Monolithic Capillary Based On Deep Eutectic Solvents

Molecular crowding is a new approach to stabilizing binding sites and improving molecular recognition. In this work, the concept was first applied to the preparation of imprinted monolithic columns for CEC. The imprinted monolithic column was synthesized using a mixture of d-zopiclone(d-ZOP)(template), methacrylic acid,ethylene glycol dimethacrylate, and poly(methyl methacrylate)(PMMA)(molecular crowding agent). The resulting PMMA-based imprinted capillary was able to separate ZOP enantiomers in CEC mode.The resolution of enantiomer separation achieved on the d-ZOP-imprinted monolithic column was up to 2.77. Some polymerization factors,such as template-monomer molar ratio, functional monomer-cross-linker molar ratio and the composition of the porogen, on the imprinting effect of resulting molecularly imprinted polymer(MIP) monolithic column were systematically investigated. CEC parameters, including pH values, the content of acetonitrile and the salt concentration on chiral separation were also studied. The results indicated the addition of PMMA resulted in MIPs with superior retention properties and excellent selectivity for d-ZOP,as compared to the MIPs prepared without addition of the crowding-inducing agent.The results revealed that molecular crowding is an effective method for improving the selectity and the degree of separation of MIPs.Deep eutectic solvents(DESs) based on choline halide is a new generation of green solvent, exhibiting similar physico-chemical properties to the traditionally used ionic liquids but much cheaper and environmentally friendly. In this paper, a new approach based on DESs-choline chloride as porogen for preparing monolithic columns for CEC was proposed. The monolithic columns were synthesized using a mixture of MAA, butyl methacrylate, EDMA, 2, 2’-Azobis(2-isobutyrontrile),choline chloride-ethylene glycol, and [HMIM]BF4. The important polymerization parameters, e.g., the kinds of ionic liquids, the ratio of ionic liquid to DESs, the proportion of functional monomer to crosslinker were systematically investigated. It was found that the resolution of the resulting monolith is increased with the increase of the content of choline chloride. In summary, the separating ability of the monoliths based on DESs is comparable with the monoliths preparing with other non-green porogen, suggesting a prospect of the green approach for monolithic column.